Introduction

The Pentax SMC DA* 300mm f/4 ED [IF] SDM is the longest tele prime lens in the current Pentax lineup. Just like a couple of its cousins it's probably a full format design although "officially" it's only compatible to APS-C DSLRs. In this scope it offers a field-of-view equivalent to 460mm in class full format terms so it qualifies as a workhorse lens for sports or wildlife photography.

The DA* 300mm f/4 is part of Pentax' professional grade lens lineup and, correspondingly,
it is a beautifully crafted lens. The outer body is obviously made of metal and
the broad, rubberized focus ring operates very smooth. The lens is also sealed against dust and moisture and The Pentax Super Protect (SP) coating on the front element has been optimized to repel dust, water and grease. Thanks to an IF (internal focusing) design the front element does not rotate and the physical size of the lens remains constant regardless of the focus setting. The deep lens hood features a removable "window"
which provides access to the filter area so it's possible to use a polarizer even with
attached hood - a simple and smart solution. A dedicated tripod mount is also provided which makes sense considering the fairly heavy weight of the lens.

The lens uses the SDM ("Supersonic Dynamic Motor") which is both virtually silent and very fast. Thanks to a "Quick Shift" system it is possible to override the AF in single-shot AF mode without the need to switch between AF and MF mode. The old drive-screw AF is also supported.